Sigma SD14 red noise, dr, fwc measured

Started Aug 16, 2011 | Discussions thread
Rodrigo Cunha Contributing Member • Posts: 701
Sensor parameters.

I now feel confident enough to deliver a new set of results, very close to reality I'm sure.

After fixing electrical ground issues in the camera, the noise dropped 3dB.

Read noise in ADUs +/- 4% : 3.88, 3.77, 3.63
Read noise in electrons +/- 4% : 38.2, 37.7, 46.1
Full well electrons (with max_adu=6700 +/- 2%) : 66000, 67000, 85000
Electrons per ADU +/- 2% : 9.85, 10.00, 12.69
Dynamic range dB +/- 4% linear : 64.74dB, 64.99dB, 65.31dB
Dynamic range EVs +/- 4% linear : 10.75, 10.80, 10.85

For a certain white balance it is possible to define an equivalent monochromatic sensor response. The following numbers are valid for the channels sum, weighted by electrons, that is, for the electrons sum, not for the ADU sum, and a white balance of ~5000k (valid for 4500k also and 5500k also... it's a broad assumption).

This are practical noise numbers, not taken from the theoretical sum of the channels.

Read noise in electrons +/- 4% : 66 (70 theoretical)
Full well electrons (with max_adu=6700 +/- 2%) : 200000
Dynamic range dB +/- 4% linear : 69.63dB
Dynamic range EVs +/- 4% linear : 11.56

The saturation ISO, considering Kodak's definition of 106% = 6700 ADUs in the green channel, which is the most sensitive, is 35. Kodak's definition is ok for controlled light in a studio, but not otherwise, since it would blow all highlights. That's why the camera's lowest ISO is 50, and even then it tends to blow highlights. It's a definition... like many others...

For 5000k black-body light the average QE, for all channels is about 29%, and for the green channel is about 12%.

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